This invention relates in general to a flat-panel display and in particular to an improved structure for a full color, high resolution capable flat-panel display which operates at a high efficiency.
A flat-panel display is an electronic display in which a large orthogonal array of display pixels, such as electro-luminescent devices, AC plasma panels, DC plasma panels and field emission displays and the like form a flat screen.
The basic structure of an AC Plasma Display Panel, or PDP, comprises two glass plates with a conductor pattern of electrodes on the inner surfaces of each plate. The plates are separated by a gas filled gap. The electrodes are configured in an x-y matrix with the electrodes on each plate deposited at right angles to each other using conventional thin or thick film techniques. At least one set of sustain electrodes of the AC PDP is covered with a thin glass dielectric layer. The glass plates are assembled into a sandwich with the gap between the plates fixed by spacers. The edges of the plates are sealed and the cavity between the plates is evacuated and filled with a mixture of neon and xenon gases or a similar gas mixture of a type well known in the art.
During operation of an AC PDP, a sufficient driver voltage pulse is applied to the electrodes to ionize the gas contained between the plates. When the gas ionizes, the dielectrics charge like small capacitors, which reduces the voltage across the gas and extinguishes the discharge. The capacitive voltages are due to charge stored and are conventionally called wall charge. The voltage is then reversed, and the sum of the driver voltage and wall charge voltages is again large enough to excite the gas and produce a glow discharge pulse. A sequence of such driver voltages repetitively applied is called the sustaining voltage, or sustainer. With the sustainer waveform pixels which have had charge stored will discharge and emit light pulses at every sustainer cycle. Pixels which have no charge stored will not emit light. As appropriate waveforms are applied across the x-y matrix of electrodes, small light emitting pixels form a visual picture.
Typically, layers of red, green or blue phosphor are alternately deposited upon the inner surface of one of the plates. The ionized gas causes the phosphor to emit a colored light from each pixel. Barrier ribs are typically disposed between the plates to prevent cross-color and cross-pixel interference between the electrodes. The barrier ribs also increase the resolution to provide a sharply defined picture. The barrier ribs further provide a uniform discharge space between the glass plates by utilizing the barrier rib height, width and pattern gap to achieve a desired pixel pitch.
Further details of the structure and operation of an AC PDP are disclosed in U.S. Pat. No. 5,723,945 titled xe2x80x9cFLAT PANEL DISPLAYxe2x80x9d and U.S. patent application Ser. No. 09/016,585, filed Jan. 30, 1998, entitled xe2x80x9cDISPLAY PANEL HAVING MICROGROOVES AND METHOD OF OPERATIONxe2x80x9d, both of which are incorporated herein by reference.
An object of this invention is to provide an improved structure for a flat-panel display, more particularly, an AC PDP which will increase the efficiency of the PDP by causing it to operate in a manner which more efficiently produces ultraviolet light to excite the phosphors. The present invention is an improved structure for a full color, high resolution capable flat-panel display which operates at a higher efficiency because of electrically isolated charge storage pads on the discharge surface.
The present invention contemplates a plasma flat-panel display comprising a first transparent substrate having a plurality of display electrodes deposited in parallel rows thereupon. In a preferred embodiment, the display electrodes are arranged in sustainer pairs. A layer of insulating film is deposited upon the surface of the first substrate covering the display electrodes. At least one electrically conductive surface pad is located upon the surface of the insulating film in association with a corresponding display electrode. An electron emissive surface coating covers at least a portion of the insulating film and may also coat the conducting surface pads.
The flat-panel display further includes a second substrate which is hermetically sealed to the first substrate. The second substrate has a plurality of micro-voids formed in a surface thereof which is adjacent to the first substrate. The micro-voids cooperate with the first substrate to define a plurality of sub-pixels which form rows parallel to the display electrodes and columns which are perpendicular to the display electrodes. The micro-voids are filled with an ionizable gas. A plurality of address electrodes are deposited upon the second substrate, each of the micro-voids correspond to an address electrode. A phosphor material is deposited within each micro-void and associated with the address electrodes.
The invention also contemplates that the display can include a pair of conductive surface pads located upon the surface of the first substrate insulating film in association with a corresponding pair of display electrodes. Each of the conductive surface pads being positioned to partially cover one of the display electrodes, thereby creating a capacitor. Further, the display can include a plurality of pairs of conductive surface pads located upon the surface of the first substrate insulating film, with each pair of conductive surface pads being associated with a corresponding pair of display electrodes.
The conductive surface pads can be formed from a metal, such as chromium, or a transparent conductive material, such as tin oxide or indium tin oxide.
The micro-voids can be formed by creating wells on the surface of the second substrate over and aligned with address electrodes. The un-voided surface areas form barrier ribs perpendicular to the display electrodes and divider ribs parallel to and separating pairs of display electrodes and conductive surface pads. Micro-voids can also be formed by etching microgrooves in the surface of the second substrate and depositing electrodes and phosphors therein by methods disclosed in U.S. Pat. No. 5,723,945, incorporated herein by reference. Alternately, parallel barrier ribs can be formed on the surface of the second substrate over and aligned with address electrodes to form the micro-voids as disclosed in U.S. Pat. No. 5,674,553, incorporated herein by reference.